SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8dbdbd0ab4e2075eedc7c06f24a45029d9b51fa8fcc778439de5948101869f' 
  AND token = 'w6MxoAc/1mhBqqv2sRA63AUZW5vrUu6yIvLkFJpQ8iY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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