SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5cf638e089f81310ccf9320f07fee88d561fb181c31bc1ad54e3b576de354f5' 
  AND token = 'MbIxeflNRn4l4h3MueHb+5QotxeEmuB6xAKLodtyfWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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