SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b03c12a63a6aef6a902ce67bfdf43892ffd9fc38507d9600c6f4a0c6d1c5e2c' 
  AND token = 'OZx3qqWxnmtO74jvOVrR/ZvNCmn+wB8VJDs6wLuRNVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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