SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300f916c3f36b45503375d86c7e25dd902d64f9cb6f52780a64d640b5b1203ba' 
  AND token = 'fGzRy9srk28lBKbPh2V4gXfglKFhesbwo1G+RYbSU7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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