SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b76a047af2fb4c3b82297b75439956ad4ab50bb115e575a2dd7d78ea06b58c1b' 
  AND token = 'ap7Lpx1gsu/pKw+J4h3JE8SgIjkvwNP60BjGFCv/6ik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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