SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b20768cafe58b8cea3221706ee3001f5af7f7ed846a25ec226291876adf40f09' 
  AND token = 'WOBkKtZ0ACsA5dVmqrbo0NknsaukJgyf6eHBY/UtFxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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