SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d81a3f92cbd50413f585038a2c7ce16fe26cc49fe969a57887cad4928b96923' 
  AND token = 'NapIbgacofpM349VWWa7mtgMjmenl2fJjgGDwxrzG0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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