SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a78604c4b2626e2531633eeb66af422cb5d5da5445a389d07482b2220535f788' 
  AND token = '0pcgX6VLPg9vBqGnFbCIEzhSO21xLQriFfnfFOs1J+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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