SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a0fdd3ba405e5271c05f276cdba11dbc6dfeaac5df1d4bd44dd263cdcc8e1a72' 
  AND token = 'JRkqRuYqWWtWgxuifU8oUe6uu241juyVA7xenT11NQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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