SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a2882e76e7d01ce987458305b8c4cbeaecf4d6b61e043f51f47bc5f0134d63fd' 
  AND token = 'rfji/p0PzxmpAvhrZlaIpkKYv+/ngdhu8LZK3KRA7UM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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