SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f4dd62cf7cbe973b05c86cc3e890d88c21279cc86f9733a6bd43fa374282f90' 
  AND token = 'YxiyQvajhpMxGbR+PGCOtjXxNEbPSRPKEVuUu2VQG80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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