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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8a138e255e93fa2eb322d6a4fa3dda7ca39e30887c6a7a9204cc4a9f60642c6' 
  AND token = 'rfg9/rjdT+uqCY3lp2CrVxi0qYn12x8qQrQVb7mzuNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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