SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f99f5f0b41823c309270ebc6077596c5c6af364b656c74dfaad9fa33c73cd48a' 
  AND token = 'DNonmY9EbnL5CxXOXcULLTrhjwPXAd4SBP3o0qpUuBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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