SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98391befdc449ba980e20ea77bee4c1f5af6ad3310b78b00764da34fe3a5740c' 
  AND token = 'OSuXislD9GHHIFvgQOfdBu06mMFgktP56IvxnKkbnSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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