SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90fe1b67aec2b9db504d32c41922a7bba2b1c657f26710cb448007924fa93dbb' 
  AND token = 'NgD105mJwOjvIm25WwS8qVlMgeIhvpHrjv+BGXMIggk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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