SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a448b41b80493ae03bfc050c7ab37b5d53f00afc71341b7fe14ba360284cfc6' 
  AND token = 'CWR9H51tZC2UPpefYtFmid/mtGTLhkkmnUqyQ8qUEkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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