SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6432e1f8581c3502e6345ee59f14b70b06db90f9e5aa2bc87be7aea956f547d' 
  AND token = 'qmKPmJY2bvjz2ES18y44sFKNsjLkBGpJeOg7WIAy+oI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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