SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5910a8862507eba9f35599c51ed4f8495d4c99f8e1e798347a136b254878248b' 
  AND token = 'FGCiXLna1/eymkLPeFIzTC6lLpYFYXTmKmbQ3jBgyhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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