SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '681c8007e34755bd42068a754f789eb8eb9413c8e7dfdb02b0971533d8a11f06' 
  AND token = 'fHPTQPjgo0FM/oUMTq/zIQ2k8bU0PScIr3qifMQPSnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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