SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90f55aafca9e74bbac2087d5dafe756a01f78374f0cc0629b2b3b552da436d5c' 
  AND token = 'OQvW4boHGDRuhDPf6obOSL1SKvklQwEpeUEFIipT7l4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}