SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74e3afe103dbc1a65eeb2fe3aa82bde1a1ea17071ac06a775ff7490a9166c778' 
  AND token = 'V7wRrVs9iYmIv3+iXbjHDP+PuSiUmTxhi8IPErRpflc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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