SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b10b72183c06d1635a2fbb9f3dfd2cb737fe2d5eb1933a408d58a305e3812be4' 
  AND token = 'MibCmAZU7QSYJEhkrR+FpqwhQ75vnb40hpCw2TsJNT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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