SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03c78fd680846c0db6dd6298564cc563a0272983e344f1e9bbec6feec905bbba' 
  AND token = 'gWC5vzG579N4hPBicLvEFnh7zd3xjwbqFhOTqxJdPmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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