SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fc3a92c0819f1f168e354b620286acc44691d7971bcd6d57fdd8542494bd88b' 
  AND token = 'rYkgjZ9vPxXha1itdHkpzOwPAwnc2CPPZkLfavtk2/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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