SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57b0e8554d32a61e1c9446ae11892629ebd3dd96e6621bdddd6e151fc2a07ed9' 
  AND token = 'L5+9WSGjkmdOotKP5AAp/XsLS27gTxpcWiJyKWlDNCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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