SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52e0adfcbe8007aa509e95a69ab7f683f5eedc4359716a3196869c6ad7de7982' 
  AND token = 'AqWVVmHsu6kQ00K+jSCo2G9LQlyXIfsFM/MYNwStcgQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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