SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c55ac6364d9854a15ae08ebd68133b6e026823cffc96fbb46154bf175809d6ab' 
  AND token = '3m+Cz0xxxSi7rvA5X/VfFjOSIel7qiDgGyLNmZRF17o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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