SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '09eaf59414f99d9f136d65aa82a1ee6b1148a2a71cb43ea531257a4699fb2bbe' 
  AND token = 'b3+93bfPENZgWWNaZBlwWiagkobJBYOTBYowDLNyGPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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