SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c459017d31961d5f2127793543c81b169c94ac064d545fc81afe743cd2edd6' 
  AND token = 'Q+nhVGxhhqfXPsRUdkVI6S0vNBSKmiDaIZmzg2Eojp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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