SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '316d0c7267bb663aa52cba6a5455d4f5550d47aa7de2798d7b10ba22366d3132' 
  AND token = '6oFtn/JFwAuNKwaLEdXkByJuLdpPjMGLj8d5bcHwpsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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