SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e135cc06ac04fdf8b237ff196c66f05a08287638eae4706ba962531c704017d' 
  AND token = 'SNMUKFZMQRPYRHNqjkkAFeXeFNBIOcrVsPV1lqarybs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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