SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc6fc961cb800e4ccd200f366192d9127f398a16427436b68df0e9d673c18122' 
  AND token = 'BMuxK0n9kC66TnvJQBEbqKPFXo3eK/hqSwqsRG3+MG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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