SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a20d2a6290704fed2d5f06561813eb5811fdc7e57e2c756398949793924ad91' 
  AND token = 'CpFPYs2Jji8Ey+kXiwQAYbE3VImhwnNT5F3BQn2NZK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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