SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42e19442ecc826658053f4285bf7c7b615602ae1dbaf79428362b34dab7c94e5' 
  AND token = 'HT8wnNhT39ebZkakdkW6iyA2F+FlGiRJsxQ6A8rSZoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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