SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '159863be09e5020283629cf5466649a59547f24b74af5fc055cc9e21764c7ed4' 
  AND token = '2w7hHjhmnrFNAqeTEgYPoWjLSkRhuy9VxRCwTRtnIOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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