SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6559c3abec2a528aff0e84648c84f7350a139fe88dee43055253135957ca7d28' 
  AND token = 'Ar5vPfCy8sXuXyEnCgg5IzgezVTQU3TSiEt94G+Vfws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}