SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7df1f36783b1f4852df1c0f9e5eb3f43714ed973b4d1ff9a2f9ebf7fafa69636' 
  AND token = 'EKEjeEKvPNFcp38J0UCxuxk1uOSGsz4H64o6FqFCZEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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