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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '503b8e8d00ffceb8d3b4d3b8e8cb5c02a2c926e0912ebfec28d7e5efb6e5e7a2' 
  AND token = 'J1ObQ52g975cqFudhyi3i3cLd4TVRagQmtM+INFTmhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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