SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0a34bd3b9062cf513bf9b0566fb7c8af5fd6a6ed8768282aaac7aea08d5217f3' 
  AND token = 'QX/PotszvNXXmoXNhhTI5BFrY3zfMZUBphjbJgD/Sy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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