SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '299d6cabd577de25e8b577947f216409bf5ccab6b979533a26351afd8d2e2884' 
  AND token = 'MSxjMiJxVIcPSPMJuCFUngyBvAE3ki8DAaaWR9EB3/M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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