SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5fe35e03a76d88b8f46379c3772d00dcf5851b79a52bbcdf5afef7642df55a0b' 
  AND token = 'kb3dt/zR/1PcmomNHrR311jl6wD5dBRZurvKtBclIUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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