SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc6159c8f2fca855f901654cc3d6bace2052e43e2ea195d9facf5278d647c286' 
  AND token = 'y7uLe4iKNRSFXHNALND+CHSXFziyM/Yv/D186N2H+s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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