SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0699798ac78471bba31401036283e959af3c74931898c4caac246410ae098f4' 
  AND token = 't3tglQEmFVcMGCvzegtXIG/tMVGDnkRYy16V3yOiRLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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