SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c15ab1608d3a8be7f39143e2d67b22aff04e88deda9372897fb354e11e766f99' 
  AND token = 'GM7AjiDTtDpRajqQOJZYmqhEPJyk6IRejotwB1sl9wM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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