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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8303e9a4f7be0b977b20e11c148d1458247286cb1ad36ad67e1decafef49d98' 
  AND token = 'Zdr6MaOCCS2Jjn4nf9jQGaURq1vyHmAhrZ4hNaW5UHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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