SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4ca4cd2cdeedc416e1cbf4e9a14737a3042b21508e86f33224c6c043b98105c' 
  AND token = '40Fw16VXTiSxNooJiGPMhdLpVjRyS3TRaIqU9c5GCF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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