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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5547443e3dde880263a7112cd72ecec277adb0612bea3c0421318ceef492e837' 
  AND token = '5zzMrQMzcvOkF9P2jBq2Uh1+RHbb30KbLvQknLApj1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}