SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6b9cefb4fd7d6dc23507b0787dc3fe716516ed2cd1ea286a8b2f4972efea585' 
  AND token = 'BrhOOF8DCjR+dmP+Sk9gPGT/sGYLMC/IqLuyHvnwYRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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