SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73255abdf01945a5c66ba1beda30583fcc3f9685f42e5f6442e7d64bf373a94c' 
  AND token = 'ljPyKeeL+Z/TcucOm1HbFZHi2YVIKrTbFo3uj0lvzGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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