SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe2d00b4db883ed91bb5c80b96dc0e09fe086ce0bb60f3b89b1be10307dae763' 
  AND token = '5+rptmRHHBpIrFo6T4IS2FcBe6RYjFVS3qCh+5jpHVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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