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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87fbc9b30eba3a8409be39077a53b3624da7fdee11502c5c8bd52f41d6e13e54' 
  AND token = 'NQPefqQoBkK6ykVhqSorDBSMuSpewVSaUeBVtR+qwcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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