SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe644c4f29ee23ea034bad9ba568798e355b650e12309a9ae38e8a4144528bbc' 
  AND token = 'tavtQGTftEzKguvcVz1ysKOmNT7VyxuMQDrczY1Zjao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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