SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74bd7f2385a07453e87526dd64ecfc8472570d729eca519934786cd50108479f' 
  AND token = 'KvEEysmLKWPN2zjoft6ZTCaQDozgrNBtMk2bjiCrfPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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