SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd869b43234f4ded80c97dd34d7fae038cecd4f250dee6b0dd8d0e22f9e3ba1b4' 
  AND token = 'VcPN9lT3DLRdeotoj+47xhQdG+tFkBBixcK2ME2RAP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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