SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a90ea6f7cb6b541eec709319900495523a2f62d50a5024af9cf9fe846b71f7cf' 
  AND token = 'mBU+WopzOhl7y880WKZDzJ7m4PihjghHwyPlRq9mxKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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